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Trench-based device with improved trench protection

a technology of trench protection and trench layer, applied in the direction of semiconductor devices, basic electric elements, electrical apparatus, etc., can solve the problem of unsatisfactory electric field distribution in the drift region, and achieve the effect of light doping and light doping

Active Publication Date: 2014-05-22
VISHAY GENERAL SEMICONDUCTOR LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

The patent text describes a new semiconductor device structure and a method of making it. The semiconductor substrate has a layer of conductivity, which is made more lightly doped than the substrate. A trench is made in this layer and filled with a conducting material. A new layer is then added on top, also made more lightly doped. A metal layer is added on top of this layer, and a first electrode is added on top of the metal layer. This new semiconductor device has improved performance and efficiency.

Problems solved by technology

However, even in these devices the electric field distribution in the drift region is still far from ideal.

Method used

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  • Trench-based device with improved trench protection
  • Trench-based device with improved trench protection
  • Trench-based device with improved trench protection

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[0026]The electric field-reducing region 120 shown in the embodiment of FIG. 2 is arranged below the bottom surface of the trench and contacts a portion of the sidewalls adjacent the bottom of the trench. The transparent layer can be formed by ion implantation and / or diffusion techniques using a suitable p-type dopant. To minimize the implantation-induced crystal damage, the implantation energy may be kept low (e.g., 25 KeV). The implantation step may be followed by an annealing step (e.g., for 60 minutes at a temperature of 950° C.). Depending on the chosen design and ratings (blocking voltage capability, leakage current and turn-off speed), illustrative geometrical dimensions and conductivities of the main layers in the structure are given below:

[0027]p-concentration: 1×1013 cm−3 to 5×1018 cm−3

[0028]p-depth: 0.05 μm to 10 μm

[0029]trench depth: 0.5 μm to 10.0 μm

[0030]trench width: 0.5 μm to 5.0 μm

[0031]mesa width (i.e. the spacing between the adjacent trenches): 0.3 μm to 30.0 μm

[...

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Abstract

A semiconductor device includes a semiconductor substrate having a first type of conductivity. A first layer is formed on the substrate having the first type of conductivity and is more lightly doped than the substrate. At least one trench is formed in the first layer. A dielectric layer lines the bottom surface and the sidewalls of the trench. A conducting material fills the trench. A lightly doped region is formed in the first layer having the second conductivity type. The lightly doped region is disposed below the bottom surface of the trench. A metal layer is disposed over the first layer and the conducting material. A first electrode is formed over the metal layer and a second electrode is formed on a backside of the substrate.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to trench-based semiconductor device, and more particularly to a trench-based semiconductor device in which stress caused by high electric fields in the vicinity of the trench is reduced.BACKGROUND[0002]Conventionally, a Schottky diode includes a heavily-doped semiconductor substrate, typically made of single-crystal silicon. A second layer covers the substrate. The second layer, called the drift region, is less heavily-doped with impurities having carriers of the same conducting type as the substrate. A metal layer or a metal silicide layer forms a Schottky contact with the lightly-doped drift region and forms the diode anode.[0003]Two opposing constraints arise when forming a unipolar component such as a Schottky diode. In particular, the components should exhibit the lowest possible on-state resistance (Ron) while having a high breakdown voltage. Minimizing the on-state resistance imposes minimizing the thickness...

Claims

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Application Information

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IPC IPC(8): H01L29/872H01L29/66
CPCH01L29/66143H01L29/8725H01L29/0623H01L29/6606
Inventor HSU, CHIH WEICHEN, MAX
Owner VISHAY GENERAL SEMICONDUCTOR LLC